The Divine Liturgy of St. Gregory is one of the liturgies authorized for use by the AntiochianWestern Rite Vicariate (AWRV). The AWRV's authorized text of the Mass is found in the Orthodox Missal. The basis of the liturgy is the Tridentine Mass as it was celebrated by the Society of Clerks Secular of St Basil (SSB), a formerly independent church that formed the basis of the Antiochian Western Rite Vicariate in 1961. It is also authorized for use within the Russian Orthodox Church Outside of Russia (ROCOR). The Mass, or Liturgy, of St. Gregory has also been authorized for use by and celebrated within the Polish Orthodox Church, the Patriarchate of Moscow, the Russian Orthodox Church Outside of Russia, and the Alexandrian Patriarchate.